Our long-range objective is to study the regulation of gene expression in human malarial parasites at the level of RNA processing and transcriptional control. As a first step, we are developing methods for the amplification and isolation of specific malarial cDNA ends, using the polymerase chain reaction technique. The fact that plasmodial ribosomes are stage-specific suggests that transcripts from the sexual and asexual stages of the parasite's lifecycle may differ in significant ways. Our preliminary data suggests that the 3' ends of transcripts coding for the circumsporozoite (CS) gene of the murine malaria P. berghei may be processed differently in sporozoites and blood stage parasites. Our intention is to extend this analysis to tbe CS genes of the human malarias P. falciparum and P. vivax. To determine whether alternative processing is a peculiarity of tbe CS gene or a general stage-specific mechanism, we will also examine the transcripts of three or more genes of P. falciparum and P. vivax that code for household enzymes or structural proteins expressed in all stages. Malarial cDNA's generated from sporozoite and blood stage RNA samples will be analyzed for 5' leader sequences, internal splicing patterns, polyadenylation sites, trans-splicing and RNA editing.